2016-12-09T07:51:59ZAn Assessment of Professional Development for Astronomy and Physics Faculty: Expanding Our Vision of How to Support Faculty's Learning About Teachinghttp://hdl.handle.net/1903/18608
An Assessment of Professional Development for Astronomy and Physics Faculty: Expanding Our Vision of How to Support Faculty's Learning About Teaching
Olmstead, Alice Rose
In this thesis, we will explore approaches to faculty instructional change in astronomy and physics. We primarily focus on professional development (PD) workshops, which are a central mechanism used within our community to help faculty improve their teaching. Although workshops serve a critical role for promoting more equitable instruction, we rarely assess them through careful consideration of how they engage faculty. To encourage a shift towards more reflective, research-informed PD, we developed the Real-Time Professional Development Observation Tool (R-PDOT), to document the form and focus of faculty's engagement during workshops. We then analyze video-recordings of faculty's interactions during the Physics and Astronomy New Faculty Workshop, focusing on instances where faculty might engage in pedagogical sense-making. Finally, we consider insights gained from our own local, team-based effort to improve a course sequence for astronomy majors. We conclude with recommendations for PD leaders and researchers.
2016-01-01T00:00:00ZWide Field of View Spectroscopy Using Fabry-Perot Interferometershttp://hdl.handle.net/1903/18592
Wide Field of View Spectroscopy Using Fabry-Perot Interferometers
Nikoleyczik, Jonathan Allen
We present a high resolution spectrometer consisting of dual solid Fabry-Perot Interferometers (FPIs). This work is intended to be an all inclusive documentation of the instrument including discussion of the design of this instrument, the methods used in data reduction, and the analysis of these data. Each FPI is made of a single piece of L-BBH2 glass which has a high index of refraction n~2.07 with a thickness on the order of 100 μm. Each is then coated with partially reflective mirrors to create a resonant cavity and thus achieve a spectral resolution of R~30,000. Running the FPIs in tandem reduces the overlapping orders and allows for a much wider free spectral range and higher contrast. We will also discuss the properties of the FPIs which we have measured. This includes the tuning of the FPIs which is achieved by adjusting the temperature and thus changing the FPI gap and the refractive index of the material. The spectrometer then moves spatially in order to get spectral information at every point in the field of view. We select spectral lines for further analysis and create maps of the line depths across the field. Using this technique we are able to measure the fluorescence of chlorophyll in plants and attempt to observe zodiacal light. In the chlorophyll analysis we are able to detect chlorophyll fluorescence using the line depth in a plant using the sky as a reference solar spectrum. This instrument has possible applications in either a cubesat or aerial observations to measure bulk plant activity over large areas.
2016-01-01T00:00:00ZNear-infrared Instrumentation For Rapid-response Astronomyhttp://hdl.handle.net/1903/18578
Near-infrared Instrumentation For Rapid-response Astronomy
Capone, John Isaac
Ɣ-ray bursts (GRBs) are the Universe's most luminous transient events. Since the discovery of GRBs was announced in 1973, efforts have been ongoing to obtain data over a broader range of the electromagnetic spectrum at the earliest possible times following the initial detection. The discovery of the theorized ``afterglow'' emission in radio through X-ray bands in the late 1990s confirmed the cosmological nature of these events.
At present, GRB afterglows are among the best probes of the early Universe (z ≳ 9). In addition to informing theories about GRBs themselves, observations of afterglows probe the circum-burst medium (CBM), properties of the host galaxies and the progress of cosmic reionization.
To explore the early-time variability of afterglows, I have developed a generalized analysis framework which models near-infrared (NIR), optical, ultra-violet (UV) and X-ray light curves without assuming an underlying model. These fits are then used to construct the spectral energy distribution (SED) of afterglows at arbitrary times within the observed window. Physical models are then used to explore the evolution of the SED parameter space with time. I demonstrate that this framework produces evidence of the photodestruction of dust in the CBM of GRB 120119A, similar to the findings from a previous study of this afterglow. The framework is additionally applied to the afterglows of GRB 140419A and GRB 080607. In these cases the evolution of the SEDs appears consistent with the standard fireball model.
Having introduced the scientific motivations for early-time observations, I introduce the Rapid Infrared Imager-Spectrometer (RIMAS). Once commissioned on the 4.3 meter Discovery Channel Telescope (DCT), RIMAS will be used to study the afterglows of GRBs through photometric and spectroscopic observations beginning within minutes of the initial burst. The instrument will operate in the NIR, from 0.97 μm to 2.37 μm, permitting the detection of very high redshift (z ≳ 7) afterglows which are attenuated at shorter wavelengths by Lyman-ɑ absorption in the intergalactic medium (IGM).
A majority of my graduate work has been spent designing and aligning RIMAS's cryogenic (~80 K) optical systems. Design efforts have included an original camera used to image the field surrounding spectroscopic slits, tolerancing and optimizing all of the instrument's optics, thermal modeling of optomechanical systems, and modeling the diffraction efficiencies for some of the dispersive elements. To align the cryogenic optics, I developed a procedure that was successfully used for a majority of the instrument's sub-assemblies.
My work on this cryogenic instrument has necessitated experimental and computational projects to design and validate designs of several subsystems. Two of these projects describe simple and effective measurements of optomechanical components in vacuum and at cryogenic temperatures using an 8-bit CCD camera. Models of heat transfer via electrical harnesses used to provide current to motors located within the cryostat are also presented.
2016-01-01T00:00:00ZProbing the Multiphase Interstellar Medium and Star Formation in Nearby Galaxies through Far-infrared Spectroscopyhttp://hdl.handle.net/1903/17261
Probing the Multiphase Interstellar Medium and Star Formation in Nearby Galaxies through Far-infrared Spectroscopy
Herrera Camus, Rodrigo
We present a study of different aspects of the multi-phase interstellar medium (ISM) of nearby galaxies, including detailed analysis of the low-excitation ionized gas, the thermal pressure (Pth) of the neutral gas, the dust-to-gas mass ratio (DGR) in low-metallicity environments, and the use of far-infrared transitions as tracers of the star formation rate (SFR). We based our work on the largest sample to date of spatially-resolved, infrared observations of nearby galaxies drawn from the KINGFISH and ``Beyond the Peak'' surveys.
We use deep infrared observations to study the DGR of the extremely metal-poor galaxy I Zw 18. We measure a DGR upper-limit of 8.1x10^{-5}. This value is a factor of ~8 lower than the expected DGR if a linear correlation between DGR and metallicity, as observed in spirals, were to hold.
Based on the line ratio between the [NII] 122 and 205 um transitions, for 140 regions selected from 21 galaxies we measure electron densities of the singly-ionized gas in the ne~1-230 cm^{-3} range, with a median value of ne=30 cm^{-3}. We find that ne increases as a function of SFR and radiation field strength.
We study the reliability of the [CII] and [NII] 122 and 205 um transitions as SFR tracers. In general, we find good correlations between the emission from these fine-structure lines and star formation activity. However, a decrease in the photoelectric heating efficiency in the case of the [CII] line, or collisional quenching of the [NII] lines, can cause calibrations based on these transitions to underestimate the SFR.
Finally, for a sample of atomic-dominated regions selected from 31 galaxies, we use the [CII] and HI lines to measure the cooling rate per H atom and Pth of the cold, neutral gas. We find a \pt\ distribution that can be well described by a log-normal distribution with median Pth/k~5,500 K cm^{-3}. We find correlations of increasing Pth with radiation field intensity and SFR, which is consistent with the results from two-phase ISM models in pressure equilibrium.
2015-01-01T00:00:00Z